Phase change inks

Abstract

Disclosed is a phase change ink composition comprising (a) a nonpolymeric ester compound ink vehicle having a melting point of at least about 60° C.; (b) a conductivity enhancing agent; (c) a colorant; (d) an optional antioxidant, and (e) an optional UV absorber.

What is claimed is:  
     
       1. A phase change ink composition comprising (a) a nonpolymeric ester compound ink vehicle having a melting point of at least about 60° C., wherein the ink vehicle is a sugar ester, an amino acid ester, a cholesteryl ester, a carboxylic ester, an unsaturated ester, an alcohol ester, a benzoate ester, an acetate ester, or a mixture thereof; (b) a conductivity enhancing agent; (c) a colorant; (d) an optional antioxidant, and (e) an optional UV absorber. 
     
     
       2. An ink composition according to claim  1  wherein the ink vehicle is β-ribo furanose 1,2,3,5-tetroacetate, 1-thio-β-gluocose tetraacetate, β-ribo furanose 1-acetate 2,3,5-tribenzoate, β-ribo pyranose 1,2,3,4-tetra acetate, methyl-α-mannopyranoside 2,3,4,6-tetra acetate, α-glucose pentaacetate, β-glucose pentaacetate, sorbitol hexaacetate, sucrose octaacetate, pentaerythritol tetraacetate, N-benzoyl threonine methyl ester, N-benzoyl tyrosine ethyl ester, N-(tert-butoxy carbonyl)aspartic acid 4-benzyl ester, N-oleoyl tryptophan ethyl ester, N-α-methoxycarbonyl tryptophan methyl ester, N-(2,4-dinitrophenyl)alanine methyl ester, N-acetyl tryptophan ethyl ester, N-acetyl tyrosine ethyl ester monohydrate, N-(tert-butoxy carbonyl)leucine N-hydroxysuccinimide ester, N-(4-nitrobenzoyl)glutamic acid diethyl ester, cholesteryl acetate, cholesteryl caprylate, cholesteryl chloroformate, cholesteryl heptylate, cholesteryl hydro cinnamate, cholesteryl palmitate, cholesteryl pelargonate, cholesteryl stearate, tetraethyl-1,1,2,2-ethanetetracarboxylate, methyl 3-isoquinoline carboxylate, methyl-4,6-dimethyl-2-oxo-2H-pyran-5-carboxylate, methyl indole-4-carboxylate, methyl-2-oxo-2H-pyran-5-carboxylate, methyl(2-chloro-1-methylethylidene)hydrazine carboxylate, methyl 4-allyl-3,5-dioxo-1-cyclohexane carboxylate, dimethyl-2-thioxo-1,3-dithiole-4,5-dicarboxylate, dimethyl(4-nitrobenzyl)malonate, diethyl-2,6-dimethyl-3,5-pyridine dicarboxylate, diethyl-4-ethyl-1,4-dihydro-2,6-dimethyl-3,5-pyridine dicarboxylate, bis(2-hydroxyethyl)terephthalate, methyl-2-chloro-α-cyanocinnamate, pentaerythritol tetrakis(3,5-ditert-butyl-4-hydroxyhydro cinnamate), methyl-3-aminocrotonate, 1,2,3-propanetriol tris(hexa decanoate), ascorbic acid 6-palmitate, triethylene glycol di-p-tosylate, 1,3-propanediol di-p-tosylate, phenyl-1-hydroxy-2-naphthoate, methyl diphenylglycolate, methyl-4-acetoxy benzoate, ethyl 3-hydroxybenzoate, methyl-2-bromo-5-nitro-benzoate, methyl-3,5-dichloro-4-hydroxy benzoate hydrate, methyl-3,5-dinitrobenzoate, methyl-2,5-dihydroxy benzoate, methyl-2,6-dihydroxy-4-methyl benzoate, methyl-3,5-dibromo-4-methyl benzoate, methyl-3,5-dibromo-4-hydroxy benzoate, 4-(2,3-epoxyhexyloxy)phenyl 4-(decyloxy)benzoate, 1,3-propanediol bis(4-amino benzoate), pentaerythritol tetrabenzoate, methyl-3,5-dibromo anthranilate, vanillin acetate, α-(trichloro methyl)benzyl acetate, phenacyl-4-(bromomethyl)phenyl acetate, 4-nitrophenyl acetate, 4-nitrophenyl trimethyl acetate, methyl-3,5-dihydroxy phenyl acetate, methyl-2-acrylamido-2-methoxy acetate, hydroquinone diacetate, 5-nitro-2-furaldehyde diacetate, 1,4-dihydro-1,4-methanonaphthalene-5,8-diol diacetate, 1,2,4-phenenyl triacetate, or mixtures thereof. 
     
     
       3. An ink composition according to claim  1  wherein the ink vehicle is present in the ink in an amount of at least about 40 percent by weight of the ink, and wherein the ink vehicle is present in the ink in an amount of no more than about 90 percent by weight of the ink. 
     
     
       4. An ink composition according to claim  1  wherein the conductivity enhancing agent is diethyl-(4-aminobenzyl)phosphonate, diethyl-(phthalimidomethyl)phosphonate, diethyl-(2,2,2-trifluoro-1-hydroxyethyl)phosphonate, diphenyl succinimidyl phosphate, dihexadecyl phosphate, undecylenic acid zinc salt, zinc bis(2,2,6,6-tetramethyl-3,5-heptanedionate), zinc cyclohexanebutyrate, zinc stearate, or mixtures thereof. 
     
     
       5. An ink composition according to claim  1  wherein the conductivity enhancing agent is present in the ink in an amount of at least about 20 percent by weight of the ink, and wherein the conductivity enhancing agent is present in the ink in an amount of no more than about 45 percent by weight of the ink. 
     
     
       6. An ink composition according to claim  1  wherein the colorant is a pigment. 
     
     
       7. An ink composition according to claim  1  wherein the colorant is a dye. 
     
     
       8. An ink composition according to claim  1  wherein the colorant is present in the ink in an amount of at least about 1 percent by weight of the ink, and wherein the colorant is present in the ink in an amount of no more than about 15 percent by weight of the ink. 
     
     
       9. An ink composition according to claim  1  containing an antioxidant, wherein the antioxidant is present in the ink in an amount of at least about 1 percent by weight of the ink, and wherein the antioxidant is present in the ink in an amount of no more than about 10 percent by weight of the ink. 
     
     
       10. An ink composition according to claim  1  containing a UV absorber, wherein the UV absorber is present in the ink in an amount of at least about 1 percent by weight of the ink, and wherein the UV absorber is present in the ink in an amount of no more than about 10 percent by weight of the ink. 
     
     
       11. An ink composition according to claim  1  wherein the ink has a haze value of no more than about 25. 
     
     
       12. An ink composition according to claim  1  wherein the ink has a hardness value of at least about 70 at temperatures of from about 20 to about 25° C. 
     
     
       13. An ink composition according to claim  1  wherein the ink has a melting point of no lower than about 60° C., and wherein the ink has a melting point of no higher than about 150° C. 
     
     
       14. An ink composition according to claim  1  wherein at ink jetting temperatures the ink has a melt viscosity of no more than about 25 centipoise. 
     
     
       15. A process which comprises incorporating into an ink jet printing apparatus an ink composition according to claim  1 , melting the ink, and causing droplets of the melted ink to be ejected in an imagewise pattern onto a print substrate. 
     
     
       16. A process according to claim  15  wherein the printing apparatus employs an acoustic ink jet process, wherein droplets of the ink are caused to be ejected in imagewise pattern by acoustic beams. 
     
     
       17. A process according to claim  15  wherein the printing apparatus employs an acoustic ink jet printing process wherein droplets of the ink are formed by acoustic beams without imparting a substantial velocity component toward the print substrate, using a droplet forming force that is sufficient only to form the ink droplets, and wherein the printing process further comprises generating an electric field to exert an electrical force different from the droplet forming force on the ink droplets to move the ink droplets toward the print substrate, and controlling the electrical force exerted on the formed complete ink droplets by the electric field. 
     
     
       18. A process according to claim  15  wherein the printing apparatus employs a piezoelectric ink jet process, wherein droplets of the ink are caused to be ejected in imagewise pattern by oscillations of piezoelectric vibrating elements. 
     
     
       19. A process according to claim  15  wherein the print